300E oil consumption
At this mileage, repalcing valve guide seals only is like putting a Band Aid on a cut artery. To do the job correctly, the cylinder head will have to be removed, and a complete valve job performed with replacement of the valve guides. If you do new valve guide seals only, they will probably wear out in 10,000 miles due to the worn valve guides. Plus, if your vehicle is burning that much oil, you are risking sticking the oil control rings in the lower end of your motor, which is a repair you definitely DO NOT want to have to do.
Just my $.02.